TeamF I have tried it at your forum, and here's what was logged into console:
4454d4ab-bdf8-49f3-918c-e07742472340:1 Uncaught ReferenceError: n is not defined
at t (4454d4ab-bdf8-49f3-918c-e07742472340:1:314)
at 4454d4ab-bdf8-49f3-918c-e07742472340:1:353
Not very specific, unfortunately. The code that triggers the error looks like this:
Judging from the looks of it, this seems to be the code of the underlying library that handles the image cropping itself. However, I can't tell what exactly is going on there, as nothing else was logged both on client and server side. So maybe someone else has more information as of why this happens?
FYI @TeamF I re-enabled FoF Profile Image Crop to look at it, feel free to disable it now